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Self-assembled In 2 O 3 nanosheet networks and flowerlike nanoarchitectures, as well as single In 2 O 3 nanosheets, have been grown in situ on indium substrate by heating indium grains at 900-950 °C under the flow of O 2 in the presence of a small quantity of P 2 O 5 . The as-synthesized In 2 O 3 nanosheets were characterized by transmission electron microscopy, scanning electron microscopy, and Raman spectrum. It was found that the In 2 O 3 nanosheets were single crystals with body-centered cubic structure and dimensions of about 0.5-3 µm. A possible mechanism for the In 2 O 3 nanosheet growth was also proposed on the basis of the results of the present and previous works. This mechanism not only can explain all the experimental observations but also helps to clarify the growth mechanism of other nanostructures in the gas phase. A strong and narrow photoluminescent (PL) peak at 428 nm was observed from the nanosheets, which is attributed to radiative recombination between an electron on an oxygen vacancy and a hole on an indium-oxygen vacancy center in the In 2 O 3 nanosheets.

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Wearable pressure sensors and strain sensors with high sensitivity and large working range are essential for detecting human motions. However, fabricating wearable sensors, which are capable of detecting pressure or strain signals, still remains challenging. Herein, two kinds of novel sensors, pressure sensors and strain sensors, are fabricated using the same materials and similar fabrication processes. The sensors are fabricated by soaking cotton in graphene inks so as to avoid high temperature and toxic chemicals caused by reduction compared to traditional graphene oxide inks. The pressure sensor shows excellent performance with high sensitivity (0.12-0.41 kPa −1 ) and broad working range (0-20 kPa). The strain sensor also has outstanding sensitivity (gauge factor 22.6-83.7) and large working strain of 27%. These two sensors are further demonstrated to show the ability of detecting human activities such as breathing, wrist pulsing, respiration, etc. The low-cost and scalable fabrication along with the good comprehensive performance of the sensors makes them applicable in wearable electronic devices for human health monitoring and movements.